Cold start enrichment system



Sept. 27, 1960 c. DERMOND COLD START ENRICHMENT SYSTEM Filed March 14, 1957 mvmron mew/yam? United States Patent Patented Sept. 27, 1960 COLD START ENRICHMENT SYSTEM Lawrence C. Dermond, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Mar. 14, 1957, Ser. No. 646,012

12 Claims. (Cl. 123'-119) The present invention relates to a metering system for a fuel injection engine. More particularly, this invention involves enrichment devices which insure an adequate quantity of fuel is supplied to the system during cranking and cold running operation.

Particularly in fuel injection systems of the mass air flow type, i.e., fuel is metered in accordance with the mass of air flowing through the system, it is necessary to provide some means to supplement the normal fuel metering function when insufficient air is flowing through the system to provide an adequate fuel metering signal. Further, in a fuel injection system where fuel is: supplied in proportion to engine speed the problem arises of providing an adequate quantity of fuel when the engine is being cranked as a preliminary to starting.

The present invention is directed, therefore, to supplementing the quantity of fuel available during cranking and cold running operation. Additional fuel is supplied by providing a metering valve which can introduce supplement-al quantities 'of fuel when the engine is cranking but which will cut off the supplementary fuel when the engine has started. To continue the supplemental supplying of fuel so long as the engine is operating under cold or low air flow conditions, a unique mechanism is provided whereby manifold vacuum is superimposed upon the normal fuel metering signals which are available under these conditions.

The details as well as other objects and advantages of the subject system will be apparent from a perusal of'the appended specification.

The drawing in this case is a diagrammatic representation of a fuel injection system embodying the subject improvements. 7

An air induction casing is shown at 10 and includes a passage '12 thereth-rough. A tapered plug member 14 is mounted in the inlet end of passage 12 to form an annular venturi 16. A throttle valve 18is disposed posteriorly of venturi 16 and is intended to control the quantity of air flowing through the induction passage to the individual cylinder intake passages indicated generally at 20.

Fuel from a sump 22 is delivered by a make-up fuel pump 24 through a conduit 26 to a fuel reservoir 28. The quantity of fuel admitted to reservoir 28 is controlled through a float controlled valve mechanism 30.

A pump 32 is disposed in reservoir 28 and is adapted to be driven at engine speed whereby the fuel delivered to a conduit 34 and a fuel metering valve 36 is under a pressure proportional to engine speed. I

The metering valve 36 includes a bore 38 having an open ended sleeve 40 fixed therewithin. Sleeve 40 includes two sets of axially spaced peripheral ports 42 and 44. Ports 42 are always open and communicate the interior of the sleeve to an annular chamber 46 formed between sleeve 46 and the valve bore 38. The upper'end 48 of sleeve 40 slidably supports a sleeve 50 openat its lower end and closed at its upper end.- Sleeve 50 is adapted to cooperate with ports 44 so as to vary the flow therethrough in accordance with conditions to be discussed subsequently. Valve bore 38 includes a counterbored portion 52 at its lower end and in which a fuel inlet port 54 is formed. Port 54 communicates with fuel pressure supply conduit 34. In order to insure that the fuel supplied to the metering valve is as clean as possible a filter element 56 is mounted in counterbore 52 intermediate port 54 and thesleeve 40. An end cap 58 encloses the counterbore 52. An additional oounterbore 60 is formed at the upper end of valve bore 38 and is also enclosed by an end cap 6 2. End cap '62 is centrally perforated to permit sleeve 50 to slidably project therethrough.

A port 64 is formed in valve bore 38 and connects with a conduit 66 leading from the fuel make-up pump 24. A slidable valve-member68 is mounted within bore 38 and is adapted to'cooperate /with port 64 to control .the flow of fuel therethrough. Valve member 68 is peripherally relieved at 70 to provide a seat for one end of a spring member 72 the other end of which seats against the fixed sleeve 40. A stop member 74 is disposed in bore 38 to limit the downward movement of valve member 68. Thus, with the engine inoperative spring '72 will bias valve member 68 against stop 74 to uncover port'64. A central passage 76 is formed through valve member 68 and is c'ounterbored at 78 to receive a ball check valve 80 which is biased in a closed position by a light spring '82. The ball check valve 80 is only lightly held closed and is adapted to be opened by fuel supplied under pressure from fuel inlet port 54. Thus with the engine running fuel will flow through counterbore 52 to passage 78 lifting the ball check valve 80 off its seat to supply fuel to the interior of sleeve 40.

Counterbore 60 has a port-84 formed therein. Port 84 communicateswith a conduit 86 to return any fuel in counterbore 60 to reservoir 28. A fuel outlet port 88 is formed in bore 38 and communicates with the annular fuel chamber 46. A conduit '90 connects fuel outlet port 88 to the individual fuel nozzles 9i formed in the cylinder intake passages 20 whereby metered quantities of fuel are supplied to the individual cylinders of the engine.

Fuel pump 3-2 is adapted to supplya quantity of fuel to the metering valve 36in excess of the normal needs of the engine with the excess fuel being bypassed through ports 44 and returned through conduit 86 to the reservoir 28.

I From the foregoing it may be seen'that the quantity of fuel delivered to the outlet port 88 is determined by the position of the slidable sleeve member 50 in relation to bypass ports 44. As ports 44 are closed less fuel will be bypassed and hence more fuel supplied to the'cylinders of the engine. The position of the slidable sleeve 50 is determined by the differential effect of fuel under pressure acting on the inside thereof and a force normally proportional to the mass of air flowing through the induction passage 12 acting on the outside thereof through a mechanism indicated generally at 92 to be subsequently described.

Since fuel pump 32 delivers fuel in proportion to engine speed it is apparent that under engine cranking conditions when the engine speed is very low a quantity of fuel insufficient-for starting purposes will be supplied to the metering valve. If this situation is obviated by making pump 32 have-a sufficiently high capacity under cranking engine speeds it is apparent that its capacity will, under normal engine speeds, be greatly in excess of that required by the system. Therefore, the present invention provides means whereby the make-up fuel pump 24 may also be utilized under cranking conditions to supplement the quantity of fuel delivered to the metering valve 36. This is achieved through the conduit 66, which as already noted, is adapted to supply fuel to port 64 and the interior of bore 38 when the valve member 68 is in its lowermost position as shown in the drawing. Spring 72 is of sufficient strength to overcome the pressure of the fuel delivered by pump 32 acting on the underside of the valve member 68 under engine cranking conditions. Thus, the outputs of pumps 22 and 32 will combine to supply adequate fuel to the nozzle supply conduits 90 under engine starting conditions. When the engine starts fuel pressure from pump 32 in counterbore 52 acting on the underside of the valve member 68 will exceed the force of spring 72 raising the member upward to close off port 64 eliminating the supplemental supply of fuel which is no longer necessary. A conduit 96 communicates the supplemental fuel conduit 66 with sump 22. A simple type relief valve 98 is disposed in conduit 96 so that when the fuel pressure in either conduit 26 or 66 exceeds a given value the excess fuel from make-up pump 24 will be returned to the sump 22.

The actuation of slidable sleeve 50 of the metering valve 36 is under the control of linkage mechanism 92 which functions in the same manner as described in copending application Serial No. 608,797 Olson filed September 10, 1956, and now Patent No. 2,873,732 granted February 17, 1959. For the purposes of the present invention it will suffice to note that the mechanism 92 includes a lever 100 having one end 102 adapted to engage slidable sleeve 50 and another end 104 articulated to a rod 106 fixed to a metering control diaphragm 108. An adjustable fulcrum 110 is disposed between ends 102 and 104 to adjustably determine the mechanical advantage of the lever 100. As end 104 of lever 100 moves upwardly end 102 will move the slidable member 50 of the metering valve downwardly to reduce the opening of ports 44 and the quantity of fuel being bypassed which correspondingly increases the quantity of fuel being supplied to the individual cylinders of the engine. The opposite result, of course, obtains upon the downward movement of the control rod 106.

The upper side of the diaphragm 108 and casing 111 define a vacuum chamber 112 which under normal operating conditions contains a vacuum force which is proportional to the mass of air flowing through the induction passage 12. As described in the aforenoted copending application Serial No. 608,797 Olson, the normal metering vacuum is created by forming an annular chamber 114 in the induction passage casing which communicates with venturi 16 through radial passage 116. Thus a vacuum force is created in annular chamber 114 which is directly proportional to the mass of air flowing through the venturi. This vacuum force is communicated to the diaphragm chamber 112 through a conduit 118 such that the diaphragm 108 will be moved up wardly to increase fuel flow as the mass of air flow increases. In order to provide an adequate metering signal when the throttle valve is closed, as will be the case when the engine is idling, a passage 120 is formed in the induction casing 10 and which passage communicates at its lower end with the idle air bypass network through a restricted passage 122. When the engine is idling air will be bypassed around throttle 18, through passage 124, chamber 126 and passage 128 as more specifically described in the aforenoted copending application. The idling air flowing through chamber 126 will create a vacuum force in passage 120 which is transmitted through a conduit 130' and ultimately to main vacuum signal conduit 118 to reinforce the metering control signal under idling conditions.

It has been found that under cranking and cold running operation the main and idling vacuum forces in conduits 118 and 130 are inadequate to sutficiently enrich the combustion charge. Accordingly, an additional conduit 132 is adapted to communicate with servo chamber 112 and deliver manifold vacuum thereto. In this way manifold vacuum, when active, reinforces the metering signal to increase the flow of fuel to the cylinders of the engine. The other end of manifold vacuum C011- duit 132 communicates with a temperature controlled valve mechanism 136 of the type described in copending application Serial No. 608,853 Dolza filed September 10, 1956, and now Patent No. 2,843,098, granted July 15, 1958. Briefly, mechanism 136 includes a valve body 138 having "a, chamber 140 to which manifold vacuum is communicated through a conduit 142. A movable valve member 144 is disposed in valve chamber 140 and cooperates with a seat 146 to control the flow of manifold vacuum to conduit 132. Valve member 144 has an arm 148 articulated to its upper end and which arm is pivoted at 150. A bimetallic thermostatic coil 152 is fixed to arm 148 so as to rotate the latter in accordance with the ambient temperature. With the coil 152 in a cold condition arm 148 will hold the valve member 144 in its retracted position, as shown in the drawing, permitting manifold vacuum to communicate through conduit 132 to the servo vacuum chamber 112. A heater coil 154 is disposed adjacent thermostatic coil 152 and is connected in the engine ignition circuit such that after a timed interval coil 154 will heat the thermostatic coil 152 to rotate the arm 148 in a clockwise direction cutting off the flow of manifold vacuum to conduit 132. The arm 148 is articulated at its other end to a rod 156 which controls a fast idle throttle cam 158 as described in the aforenoted copending application.

A valve mechanism indicated generally at 160 is provided in order that manifold vacuum when admitted to diaphragm chamber 112 is not bled to atmosphere through the main and idle vacuum conduits 118 and 130. Valve mechanism 160 includes a valve element 162 including a tapered end portion 164 disposed within an enlarged portion 166 of vacuum conduit 118 to control the admission of vacuum to chamber 112. The other end of valve element 162 is fixed to a diaphragm 168. Diaphragm 168 is peripherally mounted in a casing 170 and defines therewith a chamber 172 which communicates with idling vacuum conduit 130. A spring member 174 is disposed within chamber 172 and biases diaphragm 168 and valve element 162 downwardly to close conduit 118 to the flow of manifold vacuum. Under normal operating conditions, i.e., a warm engine with throttle opened or closed the vacuum in chamber 172 will be adequate to overcome the force of spring 174 to move the diaphragm 168 upwardly and open valve 162. However, when the vacuum force in chamber 172 is below a given value, as would be the case when the engine was being cranked, the force is inadequate to retain the valve element 162 in an open position and the latter will therefore be closed by spring 174. Under these latter conditions, manifold vacuum from conduit 132 will be active in diaphragm chamber 172 to control the metering valve 36 to insure an adequate supply of fuel to the cylinders.

By this mechanism it will be seen that when the normal metering vacuum forces are adequate to control the metering diaphragm 108 they will be able to flow past the valve element 162 to the diaphragm control chamber 112. However, when manifold vacuum controls the metering diaphragm actuation, the mechanism 160 insures that the manifold vacuum force will not be bled to the atmosphere. The combination of the novel metering valve 36 and the vacuum controlling mechanism 160 cooperate to insure that a suitably enriched fuel mixture is provided to the engine when the normal control forces are inadequate to meet the demand.

Orifices or restrictions shown in conduits 130 and 132 are provided to meter the particular vacuum force to value required for satisfactory operation of the system. It is apparent that the orifice size will vary in accordance with operating characteristics of a particular engine.

, I claim:

1. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air U to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a first pump for supplying fuel under pressure, conduit means for communicating said first pump with the individual cylinders of the engine, valve means disposed intermediate said pump and said conduit means for controlling flow of fuel through said valve in accordance With the mass of air flowing through said venturi, a second pump for supplying an additional quantity of fuel to said valve means, said valve means including a bore, a member slidably mounted in the bore, fluid pressure from said first pump acting on said member to normally block the delivery of said additional fuel to the valve means, and spring means biasing said member to a position permitting said first and second pumps to deliver fuel to said valve means during the cranking operation of said engine.

2. A fuel injection system as set forth in claim 1 in which said bore includes a port for receiving fuel from the second pump, said slidable member cooperating with said port to control the flow of secondary pump fuel to the valve means.

3. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said pass-age, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating saidfuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member with said venturi, second conduit means connecting said member With said induction passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, means for blocking the flow of vacuum through said first and second conduit means, and temperature responsive means for interrupting the flow of manifold vacuum in said third conduit means.

4. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member with said venturi, second conduit means connecting said member with said induction passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, a valve member for controlling the flow of vacuum through said first and second conduit means, an element biasing the member to a position blocking the flow of vacuum through the first and second conduits, a device responsive to the vacuum force in the first and second conduits for opening the valve member, and temperature responsive means for interrupting the flow of manifold vacuum in said third conduit means.

5. A fuel injection system as described in claim 4 in which said vacuum responsive device comprises a diaphragm operatively connected to the valve member.

6. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with aes gora 7 6 the individual cylinders of the engine, valve means dis: posed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordancewith the mass of air flowingthrough said venturi, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member With said venturi, second conduit means connecting said member with said induce tion passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, means for preventing manifold vacuum from bleeding through said first and second conduit means when the vacuum force in the third conduitexceeds that in the first and second conduits.

7. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a mechanism for controlling said valve means including a vacuum responsive member, a first conduit connecting said member with said venturi, a second conduit connecting said member with said induction passage posteriorly of said throttle .valve, and a third conduit communicating said member with manifold vacuum, a valve member for controlling flow .through said first and second conduits, a diaphragm connected to saidmember, means communicating the diaphragm with the first and second conduits, and a spring member biasing said diaphragm to close the valve member to prevent mani fold vacuum bleeding .the first. and secondconduits when the vacuum force in the third conduit exceeds that in the first and second conduits.

8. A fuel injection system for an. internal. combustion engine comprising an induction passage for. delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, means for supplying an additional quantity of fuel to said valve means, said valve means including a member normally blocking the delivery of said additional fuel to the valve means, and means for moving said member to a position permitting said additionalfuel supplying means to deliver fuel to said valve means dur-' ing the cranking operation of said engine, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member with said venturi, second conduit means connecting said member With said induction passage posteriorly of said throttle valve, and third conduit means communicating said member With manifold vacuum, and means for blocking the flow of vacuum through said first and second conduit means.

9. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance With the mass of air flowing through said venturi, a pump for supplying an additional quantity of fuel to said valve means, said valve means including a v fuel to said valve means during the cranking operation of said engine, a mechanism for controlling said valve means including a vacuum responsive member, first con duit means connecting said member with said venturi, second conduit means connecting said member with said induction passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, means for blocking the flow of vacuum through said first and second conduit means, and temperature responsive means for blocking the flow of manifold vacuum in said third conduit means.

10. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, :1 throttle valve disposed in said passage posten'orly of said venturi. a first pump for supplying fuel un der pressure, conduit means for communicating said first pump with the individual cylinders of the engine, valve means disposed intermediate said pump and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a second pump for supplying an additional quantity of fuel to said valve means, said valve means including a member normally blocking the delivery of said additional fuel to the valve means, and means for moving said member to a position permitting said first and second pumps to deliver fuel to said valve means during the cranking operation of said engine, said first pump being adapted to interrupt the delivery of fuel from the second pump when the engine becomes operative, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member with said venturi, second conduit means connecting said member with said induction passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, means for blocking the flow of vacuum through said first and second conduit means, and temperature responsive means for blocking the flow of manifold vacuum in said third conduit means.

11. A fuel injection system for an internal combustion engine comprising an induction passage for delivering air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a source of fuel under pressure, conduit means for communicating said fuel source with the individual cylinders of the engine, valve means disposed intermediate said fuel source and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, means for supplying an additional quantity of fuel to said valve means, said valve means including a member normally blocking the delivery of said additional fuel to the valve means, and means for moving said memher to a position permitting said additional fuel supplying means to deliver fuel to said valve means during the cranking operation of said engine, a mechanism for controlling said valve means including a vacuum responsive member, first conduit means connecting said member with said venturi, second conduit means connecting said member with said induction passage posteriorly of said throttle valve, and third conduit means communicating said member with manifold vacuum, means for preventing manifold vacuum from bleeding through said first and second conduit means when the vacuum force in the third conduit exceeds that in the first and second conduits.

12. A fuel injection system for an internal combustion engine comprising an induction passage for deliver ing air to the cylinders of said engine, a venturi formed in said passage, a throttle valve disposed in said passage posteriorly of said venturi, a first pump for supplying fuel under pressure, conduit means for communicating said pump with the individual cylinders of the engine, valve means disposed intermediate said pump and said conduit means for controlling flow of fuel through said valve in accordance with the mass of air flowing through said venturi, a second pump for supplying an additional quantity of fuel to said valve means, said valve means including a member for controlling the delivery of said additional fuel to the valve means, and means for moving said member to a position permitting said first and second pumps to deliver fuel to said valve means during the cranking operation of said engine, fuel under pressure from said first pump being adapted to actuate said member to block the delivery of fuel from the fuel pump to the valve means when the engine becomes operative.

No references cited.

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